The county is named for the City of Tehama. The origin of the name is not known. Suggested possible roots are the Arabic word تهامة tehama ("hot low-lands"), the Spanish word tejamanil (shingle), or "high water" in the dialect of local Native Americans.

The legacy of racism in Tehama County includes the January 1886 forced removal of Red Bluff's Chinese population, followed by the August 1886 torching of Red Bluff's Chinatown by arsonists. [4] The January 29th, 1886 edition of The Daily Alta detailed 'The Anti-Coolie Move' and confirms that a secret anti-Chinese meeting was convened in the town of Tehama, and an organization established to remove the estimated 2,000 Chinese in and around Vina. Secret daily anti-Chinese caucuses in Red Bluff were also held. [5]

The township of Corning, notably the Maywood Colony was remarkably strident in its profession of racist practice. The Maywood Colony was a large scale agricultural development of Warren N. Woodson, which was marketed nationally through many newspapers and periodicals. An advertisement in the February 1906 edition of Better Fruit...Better Vegetables proclaimed "There are no Japs, Chinese, Italians, Negroes, or other objectionable foreign elements being mixed up with us. They are not here because they are given no encouragement. They are not employed." [6]

There were 21,013 households out of which 32.9% had children under the age of 18 living with them, 54.6% were married couples living together, 11.6% had a female householder with no husband present, and 29.1% were non-families. 24.0% of all households were made up of individuals and 11.5% had someone living alone who was 65 years of age or older. The average household size was 2.62 and the average family size was 3.08.

In the county the population was spread out with 27.4% under the age of 18, 7.8% from 18 to 24, 25.7% from 25 to 44, 23.2% from 45 to 64, and 15.9% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 97.7 males. For every 100 females age 18 and over, there were 95.0 males.

The median income for a household in the county was $31,206, and the median income for a family was $37,277. Males had a median income of $30,872 versus $22,864 for females. The per capita income for the county was $15,793. About 13.0% of families and 17.3% of the population were below the poverty line, including 24.0% of those under age 18 and 9.2% of those age 65 or over.